Intravenous devices are vital instruments for many medical procedures. Intravenous devices, or "I.V.'s" transport parenteral solutions (e.g., solutions containing antibiotics) into the body when physical ingestion is not possible or not as efficient. Before this invention, precise regulation of the fluid or solution flow was a time-consuming process which required counting and timing the flow drops. This invention allows a medical technician or nurse to precisely regulate the I.V. flow rate in a matter of seconds. It also allows doctors and following care personnel to instantly view the flow rate set by the prior care giving shift.
One of the most inventive features of the present invention is the use of a diaphragm and drop former stylus or icicle for highly accurate and graduated reproducible flow results. Because I.V. systems operate at micro pressure ranges, even the smallest resistance in the fluid path can cause inaccuracy in the fluid flow rate. The present invention achieves a high degree of flow freedom with limited flow restriction. Because capillary attraction plays an important hydrostatic role in the flow of aqueous solutions at micro pressures, the drip stylus coacts with capillary attraction to assure an accurately formed globule from drop to drop even if the controller is at an "off vertical" attitude.
The present invention is further novel, in that since atmospheric pressure also plays an important role in low pressure fluid dynamics, the fluid passages are configured for low resistance passage of fluid eliminating choke junctures and the like.
Numerous devices have been developed for gravitational fluid I.V. fluid systems claiming to be accurate not only in drop rate but also in flow control. Many of these devices rely on the time-consuming and inaccurate process of counting the drips in a drip chamber to regulate flow such as those shown in McPhee, U.S. Pat. No. 3,893,468; Shelton, U.S. Pat. No. 4,261,388; Smith, U.S. Pat. No. 3,587,313. Some devices use monitors which simply register and display the flow rate such as Purcell, U.S. Pat. No. 4,383,252; Koehn, U.S. Pat. No. 3,101,710; Darlino, U.S. Pat. No. 3,163,176. Other devices utilize complicated flow control valves which do not approach the accuracy of the present invention and utilize different structure and mechanisms for control such as shown in Miller, U.S. Pat. No. 4,079,737; Marino, U.S. Pat. No. 4,634,434; Wilson, U.S. Pat. No. 3,237,774; Manske, U.S Pat. No. 4,141,379; Burke, U.S. Pat. No. 3,021,841; Mavoral, U.S. Pat. No. 4,447,226.
Over the years, various devices to control flow, such as in Burke, U.S. Pat. No. 3,021,841, Darlino, U.S. Pat. No. 3,163,176, Cannon, U.S. Pat. No. 4,300,552 and Thompson, U.S. Pat. No. 2,935,088 had been developed but without concern for a high level of accuracy and by utilizing complicated mechanisms entirely different from the present invention.
An invention such as that shown in Bron, U.S. Pat. No. 4,343,305 is unable to accurately control the formation of drop and must be positioned absolutely vertical at all times in order to have an accurate flow or virtually any flow. Furthermore, the device in Bron is not an integrated system therefore having less accuracy and control than the present invention and utilizes a different flow control system with different structure.
The structures shown in McPhee, U.S. Pat. No. 3,843,468, Shelton, U.S. Pat. No. 4,261,388 and in Burke, U.S. Pat. No. 3,332,439 utilize an adjustable clamping device applied to the tubing. The present invention's intent is to avoid such inaccurate mechanisms.
Other devices such as that described in Koehn, U.S. Pat. No. 3,101,710 disclose a flow meter to provide accurate readings but must rely on the other devices for monitoring flow control.
Mayoral, U.S. Pat. No. 4,447,226 and Miller, U.S. Pat. No. 4,079,737 utilize complicated valve mechanisms but are unable to achieve the accurate flow calibration and regulation of the present invention.
It is a principal object of the present invention to provide a intravenous flow controller which automatically compensates for the variances in fluid flow rates caused between full, partially full or almost empty I.V. fluid source containers.
It is another object of the present invention to form droplets of consistent volume by controlling the size and shape of the droplets.
It is a further object of the present invention to visually set by a physical indicator the regulated flow rate of the fluid to be passed through the inventive flow controller and injected into the patient.
It is another object of the present invention to utilize a check valve system to replace the fluid passed into the controller with the displaced gas by returning the same to the source container in relative proportions.
It is yet another object of the present invention to have a regulation indicator device and a separate turn off device allowing for the stoppage of flow while temporarily moving the patient, etc. without changing the flow regulation setting of the device.
The present invention obviates all known prior devices by a simple, economical to fabricate I.V. flow controller which can be disposed of after a single use and does not involve complicated assembly nor specialized materials. It's ease of use, maintenance, safety and fluid flow accuracy cannot be overlooked.
Numerous other advantages and features of the invention will become readily apparent from the detailed description of the preferred embodiment of the invention, from the claims, and from the accompanying drawings, in which like numerals are employed to designate like parts throughout the same.